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DLA – Gene

Genetic diseases within dogs are becoming more and more a severe issue. A much bigger headache than the heritage diseases, which can be genetically tested and determined, are the more complex medical conditions such as autoimmune disorders. The quantity and the variety of these diseases have increased significantly in the past years. Diseases such as Diabetes Mellitus, hypothyroidism as well as various forms of allergic reactions is making life difficult for breeders as well as for the owners. Why is that so? These diseases are sometimes difficult to treat and difficult to assess especially in breeding. In addition to a genetic component, environmental factors also play a decisive role in whether a dog will develop such an autoimmune disease or not. The real task of the immune system is to protect the organism from foreign intruders. As it happens, that the immune system gets out of control and instead of fighting against bacteria or viruses, it begins to destroy the body’s own tissues. Basically, this destruction can affect any tissue in the body. If, for example, the thyroid is attacked, this can result in classic hypothyroidism, i.e. underactive thyroid.

Selected genes in the body of our dogs play an important role in a functioning immune system. However, these genes, if they are present in certain combinations, can also contribute to the development of autoimmune diseases. They are called DLA genes (Dog – Leukocyte – Antigen). These genes play an important role in the immune system, such as the defence against viruses and bacteria. The DLA genes consist of the three representatives DRB1, DQA1 and DQB1. These 3 are also scientifically referred to as the haplotype. They are passed as a combination on to subsequent generations. Due to the enormous variety of pathogens that can damage a body, the presence of different alleles is particularly important. Put simply, alleles are nothing more than different variants of the same gene. They can be compared to sweaters in different colours. One sweater is green and the other is red. Still, both are sweaters. Pretending the different colours would protect you from certain illness, e.g. green protects you from a cough, you will fail the protection if you do not have a green sweater anymore. Unfortunately, many of our dog breeds today only have a very small wardrobe with a very limited colour selection of sweaters. In this case, we speak of a genetic impoverishment, which, if it occurs in the DLA genes, can lead to an increased susceptibility to autoimmune diseases. In order to keep an organism healthy and fit, the greatest possible variability in the genes, i.e. many different sweaters, is required. This is the only way for a living being to be able to react appropriately to a wide variety of conditions, including viruses and bacteria. The diversity of these DLA genes can be determined by simple testing in a single dog, but also for an entire breed.

Each breed has its specific DLA combinations. On the one hand, it reflects the history of the breeds, but also their breeding practices. By determining DLA genes, we have the opportunity to determine how many gene variants are still present in a breed and how the spread within the breed is. There are usually one or two gene combinations found in many dogs of one breed, while others have very few dogs. By knowing the DLA combinations of each dog that is in the breeding, it can be determined which combinations are to be expected in the offspring from a certain mating. It can also be ensured that these offspring do not inherit the same gene combinations from their parents. This is particularly useful when it is known that certain gene combinations are related to autoimmune diseases. Those haplotypes that are less common in a population can also be favoured in breeding. The DLA typing is an easy way to examine genes of the immune system, to collect them for each breed and to edit the variety of them in the breeding.